The applicant of the present application has invented transfer molding apparatuses capable of mass-producing thin semiconductor devices, whose thin package sections can be resin-molded with a designed thickness and without forming unfilled parts.
In one of the conventional transfer molding apparatuses, a work set in a molding die set is clamped, by a clamper, in a state where a cavity piece is upwardly moved a prescribed distance, which is greater than a designed thickness of a molded product, to an evacuating position and held at the evacuating position, and then a plunger is actuated, in a state where the clamper clamps the work, with maintaining a first resin pressure so as to fill a cavity-concave section with molten resin. After filling the resin, the cavity piece is downwardly moved into the cavity-concave section until reaching a molding position corresponding to the designed thickness of the molded product so as to flow surplus resin from the cavity-concave section toward the pot via a gate, so that an amount of the resin can be adjusted to that for producing the molded product having the designed thickness. Further, the plunger is actuated again so as to maintain a second resin pressure, which is higher than the first resin pressure, to thermally cure the resin (see Japanese Laid-open Patent Publication No. P2009-190400A).